Yuuki Tanaka (Japanese: 田中 優季, Hepburn: Tanaka Yūki, born 7 March 1990) is a Japanese professional tennis player.
On 14 December 2015, Tanaka reached her best singles ranking of world number 361. On 11 January 2016, Tanaka reached her best doubles ranking of world number 272. Tanaka has won one ITF singles title and five ITF doubles titles.
Tanaka made her WTA main draw debut at the 2016 Jiangxi International Women's Tennis Open, in the doubles event partnering Tian Ran. Her biggest ITF tournament was the $75,000 2015 Dunlop World Challenge doubles final, which she lost partnering with Luksika Kumkhum.
Tanaka was born in Chita, Aichi Prefecture and attended Yawata Elementary School and Yawata Junior High School in Chita and Sugiyama Jogakuen High School in Nagoya. She participated in her first ITF tournament at the age of 16 in July 2006, advancing through three rounds of qualifying at the $25,000 event in Nagoya before losing in the round of 32 in the main draw.
After high school she attended Waseda University in Tokyo and graduated with a degree in sports science.
Tanaka commenced playing tennis at nine years of age. In September 2010 she came runner-up in the women's singles event of the All-Japan Inter-Collegiate Tennis Tournament, losing to fellow Waseda student Hiroko Kuwata in the final. She also finished runner-up in the doubles event, partnering Waseda classmate Shiho Otake and losing to fellow Waseda students Emiko Ito and Mai Iwazaki in the final. In October 2010 she led the Waseda women's team to their fifth consecutive All-Japan Collegiate Tennis Championships title and was named MVP of the tournament. In December 2010 she partnered with Otake to win the national inter-collegiate indoor tournament in Osaka.
In March 2011 Tanaka advanced to the final of an ITF tournament for the first time, partnering with Chinami Ogi and losing to Mari Inoue and Ayumi Oka in the final of the $10,000 Miyazaki outdoor carpet tournament. She also advanced to the quarterfinals in the singles draw of the same tournament.
At the 2011 Inter-Collegiate Championship Tanaka and Otake faced Ito and Iwazake again, defeating them in the final of the women's doubles. Tanaka finished fourth in the singles competition.
Tanaka turned professional in February 2012, just prior to her graduation from Waseda. Her coach has been Atsushi Okutaka since April 2012. In June 2012 she won her first ITF tournament, partnering with her former Waseda teammate Kuwata to win the $10,000 Mie outdoor tournament, defeating Akari Inoue and Kaori Onishi in the final.
In March 2013 Tanaka won her first ITF singles title, defeating Kuwata in the final of the $10,000 Kofu hardcourt tournament. In the same month Tanaka and Kuwata were named as part of Japan's five-member women's tennis team for the 2013 Summer Universiade in Kazan, Russia.
In July 2013 the Japanese women's team won the gold medal in the women's team event at the Summer Universiade. In the main draw of the women's singles, Tanaka's teammates Sachie Ishizu and Kuwata won gold and bronze respectively. Tanaka was the top seed in the consolation draw of the women's singles and won the final against the fourth member of the Japanese team, Megumi Nishimoto. Tanaka and Ishizu were seeded fifth in the women's doubles event and lost in the quarterfinals.
In November 2015 Tanaka advanced to the second round of the 2015 Ando Securities Open, losing to eventual runner-up, top seed Nao Hibino. Later the same month Tanaka and her partner Luksika Kumkhum advanced to the final of the doubles draw of the 2015 Dunlop World Challenge, losing in a match tie-break to Akiko Omae and Peangtarn Plipuech.
In the first half of 2016 Tanaka partnered Mana Ayukawa in the final of two ITF tournaments in Mildura, Australia and Karuizawa, Japan, but the pair lost in two sets on both occasions. In August Tanaka's doubles rating had improved to her career-best No. 216 and she made her WTA main draw debut at the 2016 Jiangxi International Women's Tennis Open, partnering China's Tian Ran in the doubles event. The pair lost to top seeds Wang Yafan and Yang Zhaoxuan in the first round.